Lithium ion batteries have been widely used in electric vehicles and consumer electronics due to their advantages such as high energy density, high output power, long cycle life, and low environmental pollution. However, when the lithium ion batteries are subjected to abnormal conditions such as extrusion, collision, or puncture, they can easily to catch fire or explode, causing serious problems. Therefore, the safety issue of the lithium ion batteries greatly limits the disclosure and popularization of the lithium ion batteries.
A large number of experimental results show that an internal short circuit in a battery is the ultimate cause of safety hazards of the lithium ion batteries. In order to avoid the internal short circuit in the battery, researchers tried to improve the separator structure, battery mechanical structure and so on. Some of these studies have improved the safety performance of the lithium ion batteries by modifying the design of current collectors.
The temperature in the battery may rise when an internal short circuit occurs in the battery due to abnormal conditions such as collision, extrusion, or puncture and on the like. According to a technical solution in the related art, there is a technical solution in which alloy having a low melting point is added into the material of a metal current collector. With increasing of the temperature of the battery, the alloy having low-melting point in the current collector begins to melt, thereby resulting in a broken circuit of an electrode plate and cutting off the current. In this way, the safety of the battery is improved. According to another technical solution in the prior art, a multilayered current collector is adopted, in which both sides of a resin layer are connected with metal layers to form a composite. When the temperature of the battery reaches a melting point of the material of the resin layer, the resin layer of the current collector melts to damage the electrode plate, thereby cutting off the current and enhancing the safety of the battery.
However, these solutions in the related art cannot effectively prevent the occurrence of the internal short circuit in the lithium ion battery, and cannot guarantee that the battery can continue to operate under the abnormal conditions. In the above solutions, the temperature in the battery would still rise sharply after the internal short circuit occurs in the battery. When the battery temperature rises sharply, danger of varying degrees would still occur if the safety component cannot respond quickly. In these solutions, even the safety component responds and successfully avoids the hazard of the battery, the battery cannot continue to operate.
Therefore, it is necessary to provide designs of a current collector and a battery that can effectively prevent accidents such as firing and explosion caused by the occurrence of the internal short circuit under the abnormal conditions such as collision, extrusion, or puncture, without affecting the normal operation of the battery.